Electronics > Manufacturing & Assembly

Board too big to fab cheaply? (6x8")

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TheWelly888:

--- Quote from: justanothercanuck on December 28, 2012, 11:41:40 am ---....and I think it would disrupt the look of the board, and the premise of the project...  and there are some components I just can't convert, because they're ~30 years old.

--- End quote ---
I get the impression that the appearance of the finished board is important? If you want a certain colour for the substrate then you have no choice but to pay more....

mariush:
Another idea... perhaps it would be cheaper to make the board a two layer one and use additional small pcbs that mount vertically to make room on the big board... kind of like how power supplies use small dc-dc converters on separate boards:

like you see in this picture : http://www.techpowerup.com/reviews/Silverstone/ST45SF-G/images/in_VRMs3.jpg

Not sure if there'd be a problem with the additional resistance of the connectors and trace lengths when connecting the pcbs together though.

justanothercanuck:
I guess I can spill the beans a little...  I'm trying to build a 70s/80s microcomputer from scratch...  I'm hoping to keep it as classic looking as possible...

Anywho, I can move the power supply to its own board, and move the memory/IO logic chips to a riser board, but the main board (containing the MPU, ROM, and half the RAM) still remains. 

And it leaves out how I would interconnect all these PCB fragments.  I was tinkering with the idea of making a backplane that other boards would connect to (UART/serial, the other half of the RAM, video, sound, maybe DMA... FDC...  I'm getting ahead of myself here), but the only connection method I could think of that would provide adequate contacts is a PCI connector.

I'm not that keen on slimming the board down to 2 layers... because of the busses running down both sides of the chips, running power lines might not be possible...  I suppose theoretically I could move the busses to a single side, but I'm pretty sure I would still wind up using both layers for signal traces, which makes running power and ground planes a pain.

But I'll keep thinking about it...  I really want to see this project to the end, I was just hoping it would be cheaper so others could also build one of their own.

free_electron:
fab it at iteadstudio. it'll be cheap.

peter.mitchell:
Just wondering, did this ever get completed, if so, do you have pics?

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